5. Conclusions and recommendations
In this study, we proposed three ship collision risk indices: index of speed dispersion, degree of acceleration and deceleration, and number of ship domain overlaps. The Lloyd's MIU AIS ship movement database is applied in this study after a data-cleansing procedure. Based on the three risk indices, Legs 4W, 5W, 11E, and 12E are considered as the most risky legs in the Strait. The risk reduction solutions should be prioritized being implemented in the above-mentioned four legs. It should be pointed out that quite a number of cargo vessels (around 25%) sail with a speed beyond speed limit, which results in higher potentials of vessel collision. Impact analysis indicates that the safety level would be significantly enhanced if all the vessels follow the passage guidelines. The speed limit and passage notes are just a recommended rule for vessels passing through the Strait at present. However, according to the review of maritime transport 2008 published by the United Nations Conference on Trade and Development, global maritime trade is predicted to increase by 44% in 2020 and doubled by 2031 (UNCTAD, 2008). This would result in an increase of the maritime traffic volume through the Singapore Strait accordingly. By then, the necessary risk reduction solutions such as compulsory speed limit should be implemented to assure the safe navigation in the Singapore Strait.